Biology subjects

Gosti, G.

Publications and source records attributed to Gosti, G..

7 recordsLinked to original sources

bioRxiv2025

Inheritance entropy quantifies epigenetic regulation of cell-cycle exit in human bone marrow stromal cells

Human bone marrow stromal cells (BMSC) include skeletal stem cells with ground-breaking the-rapeutic potential. However, BMSC colonies have very heterogeneous in vivo behaviour, due to their different potency; this unpredictability is the greatest hurdle to the development of skeletal regeneration therapies. Colony-level heterogeneity urges a fundamental question: how is it possible that one colony as a collective unit behaves differently from another one? If cell-to-cell variability were just an uncorrelated random process, a million cells in a transplant-bound colony would be enough to yield statistical homogeneity, hence washing out any colony-level traits. A possible answer is that the differences between two originating cells are transmitted to their progenies and collectively persist through an hereditary mechanism. But non-genetic inheritance remains an elusive notion, both at the experimental and at the theoretical level. Here, we prove that heterogeneity in the lineage topology of BMSC clonal colonies is determined by heritable traits that regulate cell-cycle exit. The cornerstone of this result is the definition of a novel entropy of the colony, which measures the hereditary ramifications in the distribution of inactive cells across different branches of the proliferation tree. We measure the entropy in 32 clonal colonies, obtained from single-cell lineage tracing experiments, and show that in the greatest majority of clones this entropy is decisively smaller than that of the corresponding non-hereditary lineage. This result indicates that hereditary epigenetic factors play a major role in determining cycle exit of bone marrow stromal cells.

biophysics↗

bioRxiv2025

Topology, Kinetics and Inheritance in Clonal Colonies of Bone Marrow Stromal Cells

Bone marrow stromal cells (BMSC) - which include skeletal stem cells - are a promising tool in regenerative medicine. However, their heterogeneous and unpredictable in vivo behaviour remains a critical barrier preventing the development of standardized therapeutic approaches for skeletal tissue regeneration. Several studies have attempted to identify in vitro features that could correlate with the in vivo differentiation properties, yet the mechanisms ruling BMSC heterogeneity remain poorly understood. Here, using time-lapse imaging, we lineage-trace 32 single-cell-derived BMSC colonies through seven generations. We observe significant inter-colony and intra-colony heterogeneity in lineage topology (determined by the number of senescent or apoptotic cells) and in replicative kinetics (measured from proliferating cells only). Interestingly, topology and kinetics result strongly correlated, suggesting the existence of regulatory factors linking the non-dividing/apoptotic subpopulations with proliferating cells. Furthermore, BMSCs display highly synchronized cell cycles during early generations, indicating stage-specific regulatory mechanisms through which cells influence each other. By employing a non-interacting population growth model, we demonstrate that the observed synchronisation cannot be explained by an uncorrelated branching process; instead, cell-to-cell correlation of division times must exist. Our findings reveal fundamental mechanisms governing BMSC heterogeneity and growth dynamics that may inform strategies to control their regenerative potential.

biophysics↗

bioRxiv2024

Bone pain in Fibrous dysplasia does not rely on aberrant sensory nerve sprouting or neuroma formation

Bone pain is a major symptom of many skeletal disorders. Fibrous dysplasia (FD) is a genetic disease with mono or polyostotic skeletal phenotype due to the post-zygotic occurrence of the causative Gs mutation. Bone pain in FD often associates with skeletal deformities and fractures or nerve impingement by the pathological tissue. However, even in the absence of complications, FD patients often complain of a chronic pain that does not correlate with their disease burden. Multiple hypotheses have been made to explain this pain. However, its pathogenetic mechanisms remain, as yet, largely unexplored. In this study, we first demonstrate that the FD mouse model EF1-GsR201C develops a painful-like behavior and an altered response to nociceptive stimuli that, as in FD patients, do not correlate with the severity of their phenotype, thus providing a reliable model to study bone pain in FD. Then, we show that in EF1-GsR201C mice, the overall pattern of skeletal innervation is preserved and that within FD lesions, sensory fibers are variably and focally distributed, mainly at perivascular sites. Finally, we provide the first analysis of a series of human FD bone biopsies showing that sensory nerve fibers are rarely detected within the pathological tissue. These data confirm that bone pain is an intrinsic and reproducible feature of FD. They also show that, albeit sensory nerve fibers are found within FD lesions and may contribute to the unpleasant sensation that accompanies the disease, pathological sensory nerve sprouting or formation of neuromas are not detected in the Gs-mutated skeleton.

pathology↗

bioRxiv2022

Reactive microglia and cytokine release entails microtubule remodeling from acentrosomal to centrosomal arrays

Microglia reactivity entails a large-scale remodeling of cellular geometry, but the role of the microtubule cytoskeleton during these changes remains unexplored. Here we show that reactive proinflammatory microglia provide a heretofore unique example of microtubule reorganization from a non-centrosomal array of parallel and stable microtubules to a radial array of more dynamic microtubules. While in the homeostatic state microglia nucleate microtubules at Golgi outposts, proinflammatory signaling induces recruitment of nucleating material nearby the centrosome and inhibition of centrosomal maturation enhances NLRP3 inflammasome activation and secretion of IL-1{beta}. Our results demonstrate that a hallmark of microglia reactivity is a striking remodeling of the microtubule cytoskeleton and suggest that pericentrosomal microtubule nucleation may serve as a distinct marker of microglia activation as well as a novel target to modulate cytokine-mediated inflammatory responses in chronic disease and tissue injury.

cell biology↗

bioRxiv2021

Inferring the stabilization effects of SARS-CoV-2 variants on the binding with ACE2 receptor

With the progression of the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) pandemic, several variants of the virus are emerging with mutations distributed all over the viral sequence. While most of them are expected to have little to no effects at the phenotype level, some of these variants presenting specific mutations on the Spike protein are rapidly spreading, making urgent the need of characterizing their effects on phenotype features like contagiousness and antigenicity. With this aim, we performed extensive molecular dynamics simulations on a selected set of possible Spike variants in order to assess the stabilizing effect of particular amino acid substitutions, with a special focus on the mutations that are both characteristic of the top three most worrying variants at the moment, i.e the English, South African and Amazonian ones, and that occur at the molecular interface between SARS-CoV-2 Spike protein and its human ACE2 receptor. We characterize these variants effect in terms of (i) residues mobility, (ii) compactness, studying the network of interactions at the interface, and (iii) variation of shape complementarity via expanding the molecular surfaces in the Zernike basis. Overall, our analyses highlighted greater stability of the three variant complexes with respect to both the wild type and two negative control systems, especially for the English and Amazonian variants. In addition, in the three variants, we investigate the effects a not-yet observed mutation in position 501 could provoke on complex stability. We found that a phenylalanine mutation behaves similarly to the English variant and may cooperate in further increasing the stability of the South African one, hinting at the need for careful surveillance for the emergence of such kind of mutations in the population. Ultimately, we show that the observables we propose describe key features for the stability of the ACE2-spike complex and can help to monitor further possible spike variants.

biophysics↗

bioRxiv2021

Asymmetric Binomial Statistics Explains Organelle Partitioning Variance in Cancer Cell Proliferation

Asymmetric inheritance of organelle and cellular compounds between daughter cells impacts on the phenotypic variability and was found to be a hallmark for differentiation and rejuvenation in stem-like cells as much as a mechanism for enhancing resistance in bacteria populations. Whether the same processes take place in the context of cancer cell lines is still poorly investigated. Here, we present a method that allows the measurement of asymmetric organelle partitioning, and we use it to simultaneously measure the partitioning of three kinds of cellular elements, i.e. cytoplasm, membrane, and mitochondria in a proliferating population of human Jurkat T-cells. For this porpoise, we use multiple live cell markers which permit us both to follow the partitioning process for multiple generations and to investigate the correlations between the partitioning of different cellular constituents. Assuming a minimal model of asymmetric partitioning where cell sub-components are divided according to a biased binomial statistics, we derived exact analytical relationships for the average fluorescence intensity and its fluctuations as a function of the generation, obtaining an excellent agreement with the experimental measurements. We found that although cell cytoplasm is divided symmetrically, mitochondria and membrane lipids are asymmetrically distributed between the two daughter cells and present a stable positive correlation with cytoplasm apportioning, which is incompatible with an independent division mechanism. Therefore, our findings show that asymmetric segregation mechanisms can also arise in cancer cell populations, and that, in this case, membrane lipids and mitochondria do not respectively segregate independently from the cytoplasm. This helps us understand the high phenotypic variability reported in these cancer cell lines. In perspective, this could be particularly relevant in the case of tumor micro-environment diversity, where comprehension of the non-genetic cell heterogeneity could pave the way to novel and more targeted therapies. Moreover, the developed experimental and theoretical apparatus can be easily generalized to different cell kinds and different cell sub-components providing a powerful tool for understanding partitioning-driven heterogeneity.

systems biology↗

bioRxiv2020

In-Silico evidence for two receptors based strategy of SARS-CoV-2

We propose a novel numerical method able to determine efficiently and effectively the relationship of complementarity between portions of protein surfaces. This innovative and general procedure, based on the representation of the molecular iso-electron density surface in terms of 2D Zernike polynomials, allows the rapid and quantitative assessment of the geometrical shape complementarity between interacting proteins, that was unfeasible with previous methods. We first tested the method with a large dataset of known protein complexes obtaining an overall area under the ROC curve of 0.76 in the blind recognition of binding sites and then applied it to investigate the features of the interaction between the Spike protein of SARS-CoV-2 and human cellular receptors. Our results indicate that SARS-CoV-2 uses a dual strategy: its spike protein could also interact with sialic acid receptors of the cells in the upper airways, in addition to the known interaction with Angiotensin-converting enzyme 2.

biophysics↗